1. Field of the Invention
The present invention relates to a composition for the prophylaxis of influenza viral infection, comprising tannic acid, an air filter comprising the same, and an air cleaner comprising the air filter.
2. Description of the Related Art
Influenza, commonly referred to as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae. The most common symptoms of the disease are chills, fever, sore throat, muscle pains, a severe headache, coughing, weakness/fatigue and general discomfort. Fever and coughing are the most frequent symptoms. In more serious cases, influenza causes complications which can be fatal.
Typically, influenza is transmitted through the air by coughs or sneezes, creating aerosols containing the virus. Influenza can also be transmitted by direct contact with bird droppings or nasal secretions, or through contact with contaminated surfaces. Airborne aerosols have been thought to cause most infections, although the most important means of transmission is not absolutely clear. Influenza viruses can be inactivated by sunlight, disinfectants and detergents. As the virus can be inactivated by soap, frequent hand washing reduces the risk of infection.
Influenza spreads around the world in seasonal epidemics, resulting in the deaths of between thousands and tens of thousands of people every year, up to millions in some pandemic years. Three influenza pandemics occurred in the 20th century and killed tens of millions of people, with each of these pandemics being caused by the appearance of a new strain of the virus in humans. Often, these new strains appear when an existing flu virus spreads to humans from another animal species, or when an existing human strain picks up new genes from a virus that usually infects birds or pigs. An avian strain named H5N1 raised the concerns of a new influenza pandemic, after it emerged in Asia in the 1990s, but it has not evolved into a form that spreads easily from human to human. In April 2009, a novel flu strain, known as influenza A/H1N1, emerged in Mexico and spread over many other nations.
In terms of virus classification, influenza viruses are RNA viruses that make up three (influenzavirus A, influenzavirus B and influenzavirus C) of the five genera of the family Orthomyxoviridae.
The genus Influenzavirus A has one species, influenza A virus. Wild aquatic birds are the natural hosts for a large variety of influenza A. Occasionally, viruses are transmitted from one to another species and may then cause devastating outbreaks or give rise to influenza pandemics. Type A viruses are the most virulent human pathogens among the three influenza types. The influenza A virus can be subdivided into different serotypes (subtypes) based on the antibody response to these viruses. The serotypes that have been confirmed in humans, ordered by the number of known human pandemic deaths, are as follows: first, H1N1 caused the Spanish flu in 1918, and the 2009 flu pandemic. H2N2 caused the Asian Flu in 1957 and H3N2 caused the Hong Kong Flu in 1968. In addition, H5N1, H7N7, H1N2, H9N2, H7N2, H7N3, and H10N7 appeared.
A more detailed description will now be given of H1N1. Influenza A (H1N1) virus (influenza A virus subtype H1N1) or simply H1N1 is the most common cause of human influenza. In addition, this subtype can infect pigs and birds.
A variant of H1N1 was responsible for the Spanish flu pandemic that killed some 50 to 100 million people worldwide over about a year in 1918 and 1919. The H1N1 genome was published in the journal of Science in 2005, reporting “When compared with today's human flu viruses, the 1918 virus had alterations in just 25 to 30 of the virus's 4,400 amino acids.” Low pathogenic H1N1 strains still exist in the wild today, causing roughly half of all flu infections in 2006.
From March of 2009, the worldwide death toll from the H1N1 virus increased. The influenza was first dubbed swine flu, but renamed as a new flu or as the new influenza A (H1N1) in Korea because the influenza A virus subtype H1N1 cannot be spread by eating pork or pork products. The World Health Organization (WHO) officially declared the outbreak to be a pandemic on Jun. 11, 2009.
According to government statistical data, more than ten thousand cases of the new flu were generated with eight serious cases hospitalized and 14 patients dying from chronic or acute complications, as of Sep. 16, 2009.
The genus Influenzavirus B has one species, influenza B virus. Influenza B almost exclusively infects humans and is less common than influenza A. The only other animals known to be susceptible to influenza B infection are the seal and the ferret. This type of influenza mutates at a rate 2-3 times slower than type A and consequently is less genetically diverse, with only one influenza B serotype. As a result of this lack of antigenic diversity, influenza B almost never causes the outbreak of a pandemic because of its limited host range.
The genus Influenzavirus C has one species, influenza C virus, to which humans, dogs and pigs are susceptible. Influenza C is less common than the other types A and B and usually only causes mild disease in children.
Among antiviral drugs currently available for the treatment of influenza are oseltamivir (trade name: Tamiflu), zanamivir (trade name: Relenza), peramivir and amantadine, with the predominant application of Tamiflu to the treatment of influenza A virus subtype H1N1. Tamiflu, a drug with a worldwide monopoly, was developed to treat avian influenza (AI). By blocking the activity of the viral neuraminidase enzyme, Tamiflu prevents new viral particles from being released by infected cells. An effective efficacy can be obtained when it is taken within 48 hours of the onset of symptoms. The main efficacy of Tamiflu is known to lie in the relief of symptoms, the warding off of secondary complications such as bronchitis or pneumonia, and a decrease of the latent period. Tamiflu has been used to treat and prevent influenzavirus A and influenzavirus B infections in tens of millions of people since 1999. Zanamivir, sold under the trade name of Relenza, is a neuraminidase inhibitor used in the treatment and prophylaxis of Influenzavirus A and Influenzavirus B.
Side effects associated with oseltamivir therapy include nausea and vomiting. Zanamivir shows high antiviral effects, but poor bioavailability, with fast release from the kidney.
Most of the anti-influenza agents developed thus far have side effects. Thus, there is the need for the development of an anti-influenza composition that is effective for the treatment and prophylaxis of influenza viral infection.
Commonly, influenza is spread via the airborne route, that is, when someone inhales the aerosols produced by the coughing, sneezing or spitting of an infected person. Influenza can also be spread by direct transmission, e.g., by way of the excretions, spit, snivel, or blood of infected persons. However, the spread of influenza results mostly from droplet infection such as by aerosol inhalation. Influenza viruses may be inactivated by sunlight, disinfectants, surfactants, e.g., soap, which are however not effective for the removal of airborne viruses.
The capture and inactivation of airborne viruses may lead to the effective prevention of influenza infection.
An air filter is an air-permeable member which can removes solid particulates from the air. Air filters are used in applications where air quality is important, such as in air cleaners, air conditioners, vacuum cleaners, humidifiers, dehumidifiers, etc., notably in building ventilation systems and in engines.
Designed to remove contaminants from the air, an air cleaner comprises a plurality of filters composed typically of a pretreatment filter for removing large size particles; a deodorizing filter for removing odor, volatile organic chemicals, formaldehyde, etc.; an HEPA filter for removing airborne particulates which have a diameter on the micrometer scale; and a median filter, arranged in front of the HEPA filter, for protecting the HEPA filter.
More filters may result in higher air-purifying performance, but increase resistance against overall air circulation. Accordingly, 3 to 5 filters are typically employed in an air cleaner.
Recently, studies have focused on functional filters which can selectively remove harmful materials in an elaborate manner or substitute beneficial materials for harmful materials. For example, filters for removing microparticulates with high efficiency or for purifying the airborne particulates which cause sick house syndrome have been developed.
Leading to the present invention, intensive and thorough research into a composition acting against new influenza A H1N1, conducted by the present inventors, resulted in the finding that a sumac extract has an inhibitory activity against influenza viruses and that a composition comprising tannic acid as an active ingredient is useful in the prophylaxis of influenza viral infection and a filter coated with the extract can effectively remove airborne influenza viruses.